For Chauncey Bailey, one of the most respected black journalists in America, last Thursday morning's trip to work should have been like any other. The editor of the Oakland Post was strolling down the pavement in Oakland, a mostly black city next to San Francisco. It was 7.30am and Bailey, 57, lived just a few blocks away.

Suddenly, a man dressed in black and wearing a mask appeared. Shots rang out and Bailey collapsed from three bullet wounds. He was dead before an ambulance arrived; the apparent victim of an assassination.

Bailey's murder has shocked the San Francisco Bay Area. It has also rippled out into the rest of America as the country comes to grips with the daylight murder of a senior newspaper editor. There is little doubt that Bailey was executed. It was the kind of ruthless murder more likely to be found on the streets of Moscow than northern California. 'This was no random act,' said Sergeant Derwin Longmire, an Oakland police spokesman.

Bailey's routine was well-known and it is likely that his killer had been monitoring his movements for some time before he struck. After the shooting, the killer was picked up by a van.

The reason that Bailey was killed appears to lie with the secretive and shadowy black Muslim sect in Oakland that Bailey was investigating. A day after he died, a series of dramatic police raids unfolded across the city, aimed at a group of Islamists centred on a business called Your Black Muslim Bakery.

The bakery was the centrepiece of a business empire founded by Yusef Bey, a black Muslim leader in Oakland whose followers preached a strict message of Islam and black political power. Bey's followers have long been the subject of intense police and media scrutiny for their alleged use of strong-arm tactics in promoting their business interests and also shutting down stores that sold alcohol. Bey was also stridently anti-homosexual and awaited trial on 27 counts of sex crimes when he died of cancer in 2003.

Bailey had written articles about Your Muslim Black Bakery and was believed to be working on further investigations when he was killed. He had recently been making enquiries in the black business community about the bakery's finances. His colleagues also told police he had recently received death threats because of his journalistic work, but had not been specific about their source.

The raids ended with seven arrests and the discovery of a cache of weapons and ammunition. Police said initial findings had linked some of the weapons to Bailey's case. 'The search warrant yielded several weapons and other evidence of value linking the murder of Chauncey Bailey to members of Your Muslim Black Bakery,' said assistant police chief Howard Jordan.

Jordan said the raids had been part of a year-long probe that was investigating charges of murder, kidnapping and other crimes. Earlier deaths have been associated with Your Black Muslim Bakery. In 1994, members of the group threatened to kill white police officers investigating an alleged beating meted out to an Oakland resident. When Bey died, his handpicked successor disappeared. His decomposed body was found six months later. One of Bey's sons was shot and killed last month.

A simple shrine of flowers and notes now marks the spot where Bailey died. There is a large stuffed bear and poster boards for people to leave messages. His death has stunned colleagues and ordinary Americans who are unused to the murder of journalists. The last reporter killed in America 'in the line of duty' was a photo editor in Florida who died as a result of the anthrax postal murders in 2001.

Bailey's colleagues are still struggling to come to terms with his death. 'I'm still thinking I'll run into him downtown, wearing a suit on his way to cover this event or that meeting, reporting the news of the black community,' said columnist Brenda Payton.